1. Field of the Invention
The present invention relates to molds and methods for manufacturing heat dissipation apparatuses, and more particularly to a mold for manufacturing a heat dissipation apparatus having large heat dissipating area.
2. Description of Related Art
It is well known that thermal modules are traditionally used in micro-electronics to help transfer heat from heat generating electronic components mounted on a printed circuit board. A typical thermal module includes a base plate, a centrifugal blower mounted to the base plate, a fin assembly located at an air outlet of the centrifugal blower and a heat pipe connecting the heat generating electronic component with the fin assembly to transfer heat therebetween.
In the thermal module, the base plate, a housing of the centrifugal blower and the fin assembly are formed together into a combination. The fin assembly is formed by a piece of insert arranged in a mold having cavities for forming the base plate and the housing of the centrifugal blower. The insert defines a plurality of concave cavities for forming fins of the fin assembly. During manufacturing of such a combination, there is always air retained in the concave cavities of the insert which causes bubbles to form in the fins of the fin assembly after molten metal is cooled. The bubbles result in residual stresses in the fins and thus decrease mechanical strength of the fins. The fins, which do not have sufficient strength, may be damaged in parting mold operation. Therefore, the fins need to be thicker to solve these problems. However, thicker fins are not preferable in view of heat dissipation effectiveness. Furthermore, the entire insert needs to be replaced when some of the concave cavities are damaged due to the damage of the fins without sufficient strength. This increases the maintenance cost of the mold. Thus, it is necessary to provide a mold, which has a lower maintenance cost and can manufacture a thermal module having thinner fins.